It is lightly stamped, from the backside "25", and upside-down, face up, above the row of threes "1". Mounted to the left adjoining main tag.

Quirky side note, unrelated: these were mounted on the fender with (factory appearing) hex head screws. There were unused holes drilled on the core support where (at least in 78) the tags were placed.

Car's a 76 Fury Salon.

So, what's the tag's purpose?

Tag in question: